Amide rule

The Amide Rule as formulated by Freudenberg states. The rotation of amides of a hydroxy acids of the D-series is always shifted to the right as compared with the rotation of corresponding hydroxy acids. 

During the interval between Vongerichten s and Schmidt s investigations, there were discovered several empirical rules through which the configuration of the a-carbon atom of many a-hydroxycarboxylic acids may be inferred. Schmidt applied three of these generalizations, the salt-acid rule and the phenylhydrazide and amide rules, to the appropriate derivatives of apionic acid Table I shows the comparisons which he published. 

Amadori rearrangement, III, 42, 43 Amide rule of rotation, I, 21, 163 Amides, of sugar acids, oxidation of, III, 165... 

The first of these was van t Hoff s principle of optical superposition, namely, that, in a compound having two or more asymmetric carbon atoms, the optical activities of the individual atoms can be added algebraically. This principle was applied with considerable success to carbohydrates by Hudson, in the form of his well known isorotation, lactone, and amide rules. These rules have been reviewed elsewhere, " and will not be discussed here. 

Voto6ek has prepared these acids and used the amide rule of rotation for identification of their respective configurations. 

Digitoxose, therefore, represents a case wherein the Hudson lactone rule fails insofar as the lactones of digitoxonic and digitoxosecarboxylic acids are concerned, a behavior paralleled by D-allonic acid lactone of which digitoxose is a derivative. At the same time, the diamide of the glutaric acid obtained on oxidation of digitoxose now obeys Hudson s amide rule in the light of the above observations and also the lactone of this acid obeys the lactone rule. 

Stiller and associatesin the Merck laboratories a little less than a year after the collaboration began isolated the lactone from concentrates, and determined its structure by classical methods to be -hydroxy-/5,/ -dimethyl-y-butyrolactone. This was synthesized and resolved into its optical isomers. The levo-rotatory lactone when condensed with /3-alanine by various pro-ceduresi >22>2 yields dextro-rotatory pantothenic acid with full biological activity. The antipode was found to be inactive. The biologically active form has, according to Hudson s amide rule, the D-configuration24.2s. 

Because the rules for organic nomenclature determine the priority of naming different carbon chains from their relative lengths, the systematic names for type AABB polyamides depend on the relative length of the carbon chains between the amide nitrogens and the two carbonyl functions of the polymer for aUphatic nylon-Ayy, when x < the lUPAC name is poly[imino-R imino(l2y-dioxo-R )]. When x > then the name is... 

The structure of 82 was established by alkaline ring cleavage to benzilic acid amide and by hydrogenolysis to (C6H5)2CH—CONH— COCfiHs. These reactions also served to eliminate 83 as the structure of the 169° compound. The other possible isomeric structure, (C6H5)2C(CN)0C0C6H5, which could have formed after 0-acylation, was ruled out by its independent synthesis from bromodiphenyl-acetonitrile and silver benzoate. 

In the N-Bz derivatives of Gly and Gly-Gly, the planar [R3Sn(IV)] moieties are bridged by -COO groups. Because of the negative inductive effect of the Ph group, which reduces the donor ability of oxygen atoms, coordination of the amide -C = O in the latter compounds could be ruled out. 

The enzymatic KR between racemic amines and nonactivated esters using a lipase as biocatalyst is shown in Scheme 7.15. In the same manner as in the transesterification of secondary alcohols, this process fits Kazlauskas rule [32], where normally if the large group (L) has larger priority than medium group (M), the (R)-amide is obtained. In general, major size differences between both groups result in better enantios-electivities ( ). 

Radical addition to conjugated systems is an important part of chain propagation reactions. The rate constants for addition of cyclohexyl radical to conjugated amides have been measured, and shown to be faster than addition to styrene. In additions to RCH=C(CN)2 systems, where the R group has a chiral center, the Felkin-Ahn rule (p. 148) is followed and the reaction proceeds with high selectivity. Addition of some radicals, such as (McsSijaSi-, is reversible and this can lead to poor selectivity or isomerization. ... 

The ammonioacetonitrile complex (206) reacts with NH3 to produce the amidine-bonded aminoacetamidine (207) complex, whereas in aqueous base it hydrolyzes to the amid o-A -bo ruled glycinamide complex (208).908 Acid-catalyzed linkage isomerization to first the O-bound form (209) precedes formation ultimately of the amino-bonded isomer (210) as the stable product upon deprotonation of the free amine above pH 6. 

The reaction of 151 with methanol to give dimethyl phosphate (154) or with N-methylaniline to form the phosphoramidate 155 and (presumably) the pyrophosphate 156 complies with expectations. The formation of dimethyl phosphate does not constitute, however, reliable evidence for the formation of intermediate 151 since methanol can also react with polymeric metaphosphates to give dimethyl phosphate. On the other hand, reaction of polyphosphates with N-methylaniline to give 156 can be ruled out (control experiments). The formation of 156 might encourage speculations whether the reaction with N,N-diethylaniline might involve initial preferential reaction of monomeric methyl metaphosphate via interaction with the nitrogen lone pair to form a phosphoric ester amide which is cleaved to phosphates or pyrophosphates on subsequent work-up (water, methanol). Such a reaction route would at least explain the low extent of electrophilic aromatic substitution by methyl metaphosphate. 

There were significantly fewer reports on organozinc compounds bearing ligands with heavier group 15 donors than those on organozinc amides. This is mainly due to the weakness of the zinc-pnictide bonds, which rules out the use of... 

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